Na atualidade, vários são os métodos de osteossíntese utilizados na reparação de fraturas de fêmur em cães, porém alguns apresentam complicações na técnica, e outros não encontram-se disponíveis na atividade profissional diária de alguns médicos veterinários da América Latina. O presente trabalho teve como objetivo desenvolver um novo modelo simples de osteossíntese, baseado na utilização de pinos de Steinmann e Schanz denominado pinos intramedulares múltiplos bloqueados (PIMB), e testar biomecanicamente a resistência as forças de flexão em comparação com a técnica de pino intramedular único (PIU). Para tanto foram utilizados fêmures bilaterais de oito cadáveres de cães com peso entre 15 a 25 quilos que foram divididos em dois grupos, o primeiro grupo composto por oito fêmures utilizou os pinos intramedulares múltiplos bloqueados e o segundo grupo composto por oito fêmures utilizou pino intramedular único, ocupando entre 40 - 42 % do canal medular como controle do Grupo 1. Os dois grupos de fêmures foram submetidos a ensaios não destrutivos para avaliar a resistência as forças de flexão, com forças entre 0 e 50 Kg, e velocidade de deslocamento de 5mm/minuto, num dispositivo de quatro pontos. Os resultados encontrados nas condições apresentadas neste estudo mostraram que a técnica de pinos intramedulares múltiplos bloqueados apresenta uma menor resistência as forças de flexão comparada com a técnica de pino intramedular único / Currently, there are several methods of fixation used in the repair of femoral fractures in dogs, but some show complications in the technique, and others are not available daily in the professional activity of some veterinarians from Latin America. This study aimed the development of a new, simple model for bone fixation, based on the use of Steinmann and threaded pins, used as multiple locked intramedullary pins (MLIP), and biomechanically test the implants resistance to bending forces. Therefore, we used bilateral femurs of eight cadaveric dogs weighing between 15-25 kg, divided into two groups; in the first group multiple locked intramedullary pins were used in eight femurs, and in the second group, the control group, we used a single intramedullary pin (SIP) occupying between 40-42% of the intramedullary canal, of eight femurs. Both groups were subjected, in a four point device, to nondestructive testing to evaluate the resistance to flexion forces, with forces varying between 0 and 50 kg, and a speed of 5mm/minute. The results under the conditions presented in this study showed that technique locked multiple pins has a lower resistance to bending forces compared with the technique of single intramedullary pin.

This thesis includes the development, construction and testing of internal organ phantoms, with focus on the liver, for biomechanical testing. Phantoms have various biomedical applications such as surgical simulations, minimally invasive surgery, soft tissue characterization, diagnostic tools and instrumentation calibration. However, there is little work present in literature regarding phantoms and the work that is currently available does not account for the non-linear viscoelastic properties as well as the Glisson’s capsule. In this work, three different phantoms are presented: a fluid-filled phantom, a perfused phantom and a hydrogel-based liver phantom. A testing apparatus is designed, built and used to measure the force-displacement data during the indentation of the phantom. The first phantom that is designed and constructed follows the basis of a fluid-filled vessel. It is composed of a linear low-density polyethylene (LLDPE) bag filled with different fluids namely: water, a 1:1 water/glycerine mixture and glycerine. The phantoms are subjected to quasi-static loading as well as relaxation testing. The effect of density and viscosity, its size, and confined and unconfined boundary conditions are characterized. The second phantom is designed to investigate the effects of hepatic macrocirculation on the biomechanical properties of the liver. The phantom is made of two-part silicone (Smooth-On, ECOFLEX 00-30), and contains a network of conduits to model the large ! iv! blood vessels in the liver. A perfusion system that captures the general features of the human hepatic circulation is used to help investigate the effects of the different flow parameters such as pressure and flow rate on the biomechanical characteristics of the liver. The perfusion system is designed to reproduce comparable pressures to the human portal vein and hepatic artery. The third phantom is made of two parts, a hydrogel inner layer with a LLDPE outer layer. The idea behind this phantom is to represent the organ as accurately as possible by accounting for the capsule that surrounds the organ as well as the biphasic (solid and fluid) nature of the organ. A biphasic poroviscoelastic model is used to model the hydrogel while the LLDPE uses a non-linear hyperelastic and viscoelastic model. Modeling is done in ABAQUS to fit the experimental data obtained from quasi-static indentation and relaxation testing using a parametric study. In conclusion, phantoms replicating the non-linear viscoelastic properties observed in organs are presented and characterized. Main Thesis Contributions • Development and characterization of a simple fluid-filled phantom to represent the mechanical properties of the liver • Development and characterization of hydrogel-based liver phantom with representation of the biphasic nature of the organ and the Glisson’s capsule. ! v! • Development and characterization of perfused liver phantom with ability to be recreated with various vessel configurations. • Development of testing set-up to characterize various phantoms.

Na atualidade, vários são os métodos de osteossíntese utilizados na reparação de fraturas de fêmur em cães, porém alguns apresentam complicações na técnica, e outros não encontram-se disponíveis na atividade profissional diária de alguns médicos veterinários da América Latina. O presente trabalho teve como objetivo desenvolver um novo modelo simples de osteossíntese, baseado na utilização de pinos de Steinmann e Schanz denominado pinos intramedulares múltiplos bloqueados (PIMB), e testar biomecanicamente a resistência as forças de flexão em comparação com a técnica de pino intramedular único (PIU). Para tanto foram utilizados fêmures bilaterais de oito cadáveres de cães com peso entre 15 a 25 quilos que foram divididos em dois grupos, o primeiro grupo composto por oito fêmures utilizou os pinos intramedulares múltiplos bloqueados e o segundo grupo composto por oito fêmures utilizou pino intramedular único, ocupando entre 40 - 42 % do canal medular como controle do Grupo 1. Os dois grupos de fêmures foram submetidos a ensaios não destrutivos para avaliar a resistência as forças de flexão, com forças entre 0 e 50 Kg, e velocidade de deslocamento de 5mm/minuto, num dispositivo de quatro pontos. Os resultados encontrados nas condições apresentadas neste estudo mostraram que a técnica de pinos intramedulares múltiplos bloqueados apresenta uma menor resistência as forças de flexão comparada com a técnica de pino intramedular único / Currently, there are several methods of fixation used in the repair of femoral fractures in dogs, but some show complications in the technique, and others are not available daily in the professional activity of some veterinarians from Latin America. This study aimed the development of a new, simple model for bone fixation, based on the use of Steinmann and threaded pins, used as multiple locked intramedullary pins (MLIP), and biomechanically test the implants resistance to bending forces. Therefore, we used bilateral femurs of eight cadaveric dogs weighing between 15-25 kg, divided into two groups; in the first group multiple locked intramedullary pins were used in eight femurs, and in the second group, the control group, we used a single intramedullary pin (SIP) occupying between 40-42% of the intramedullary canal, of eight femurs. Both groups were subjected, in a four point device, to nondestructive testing to evaluate the resistance to flexion forces, with forces varying between 0 and 50 kg, and a speed of 5mm/minute. The results under the conditions presented in this study showed that technique locked multiple pins has a lower resistance to bending forces compared with the technique of single intramedullary pin.

No description available.

No description available.

As claudicações são a principal causa de encaminhamento de equinos aos médicos veterinários e uma das maiores causas de encaminhamento destes animais aos hospitais de referência; sendo as fraturas, especialmente aquelas de ossos longos e articulares, as que têm menor índice de sucesso devido ao prognóstico reservado e alto custo do tratamento; entendendo como sucesso o retorno do animal à função ou manutenção da qualidade de vida. A articulação interfalangeana proximal (AIP) dos equinos é clinicamente importante devido à apresentação frequente de claudicação, com lesões que comprometem a vida esportiva e função do equino. O objetivo desta pesquisa foi comparar biomecanicamente as características de duas técnicas de artrodese da AIP em equinos, utilizando-se placa de compressão dinâmica (DCP) de 4.5mm e três orifícios em combinação com dois parafusos corticais transarticulares de 5.5mm oblíquos inseridos pela técnica de tração (lag screw) e placa em "Y\" de compressão bloqueada (LCP) de 5,0mm e sete orifícios, com parafusos bloquados unicorticais e um parafuso cortical de 4.5mm oblíquo transarticular inserido no orifício central da placa, pela técnica de parafuso de tração. Foram utilizadas doze peças anatômicas de membros anteriores de equinos, das quais foi isolada a porção distal do membro desde a primeira falange até o casco. Uma vez preparadas as peças, cada par foi sorteado randomicamente para cada um dos dois grupos. Os modelos experimentais foram submetidos a ensaios biomecânicos de compressão axial em ciclo único até a sua falha. O tipo de falha ocorrida na placa, nos parafusos ou nos ossos foi avaliado, assim como a força à qual ocorreram estas falhas. Não houve diferença estatística significativa entre os grupos DCP e Y-LCP, nas variáveis rigidez e força máxima, quando submetidas a compressão axial até sua falha. Mesmo não havendo diferença entre as duas técnicas cirúrgicas na variável rigidez, a técnica Y-LCP possibilitou um procedimento menos invasivo e com menor tempo cirúrgico. Conclui-se que, as propriedades biomecânicas das duas técnicas de fixação (DCP e Y-LCP) são semelhantes nas condições testadas. / Lameness is the main cause of sport horses\' owners consulting equine veterinarians and one of the highest cause to send these animals to the reference hospitals. Long bones and joint fractures have the lesser rate of success, consequence of the hight cost of the treatment and poor prognosis. Understanding as success the return of the horse to previous athletic performance or at least to have useful life. The proximal interphalangeal joint (PIPJ) is clinically important because the injuries that involve it may threaten the horses sport life or its usefulness. The objective of this study was to compare the biomechanical properties of two PIPJ arthrodesis techniques using 4.5mm dynamic compression plate (DCP) in conjunction with two oblique abaxial transarticular 5.5mm cortical screws inserted in lag fashion and 5.0mm Y locking compression plate (Y-LCP) with unicortical locking screws and one axial transarticular 4.5mm cortex screw inserted in lag fashion through the midle plate hole. It was used twelve cadaveric adult equine forelimbs from the first phalanx to the foot. After full-limb preparations, each forelimb pair was randomly assigned to one of two treatment groups. Constructs were submited to axial compression single cycle to failure biomechanical testing. The failure of the screws, plate or bone, and the force at wich it happened was evaluated. There were no significant differences in construct stiffness or max force when loaded to failure, between the DCP and Y-LCP treatment groups. Even though there was no construct stiffness diffrences between the two techniques, the Y-LCP technique provided the possibility of a less invasive procedure with a shorter surgical time. In conclusion, the biomechanical properties of both fixation techniques (DCP and Y-LCP) are equivalent under the test conditions used.

Foi realizado estudo experimental, utilizando-se vértebra de suínos, para o estudo da influência da técnica de perfuração do pedículo vertebral na resistência ao arrancamento dos implantes. A técnica de perfuração com broca seguida de macheamento do canal pedicular (técnica 1) foi individualmente comparada com as demais: perfuração com broca sem macheamento do canal pedicular (técnica 2), perfuração com fio de Kirschner com macheamento do canal pedicular (técnica 3), perfuração com sonda sem macheamento do canal pedicular (técnica 4). Três grupos experimentais foram utilizados de acordo com a preparação do orifício. O grupo I comparou a técnica 1 com a técnica 2, no qual foi estudado a influência do macheamento no canal do pedículo. O grupo II comparou a técnica 1 com a técnica 3, no qual foi estudado a influência no modo de preparo do orifício utilizando fio de Kirschner. O grupo III comparou a técnica 1 com a técnica 4, no qual foi estudado a influência da utilização da sonda no preparo do orifício. O resultados da comparação da técnica. de perfuração do orifício de acordo com os parâmetros estudados (carga máxima de arrancamento, rigidez, carga no limite de proporcionalidade, deslocamento máximo e deslocamento no limite de proporcionalidade), mostraram que não houve diferença estatisticamente significante entre as diferentes técnicas utilizadas para o preparo dos orifícios do pedículo vertebral na resistência ao arrancamento dos implantes. / An experimental study was conducted on swme vertebrae to investigate the effect of the technique of vertebral pedicle perforation on the pullout resistance of the implants. The technique of perforation with a burr followed by tapping of the pedicular canal (technique 1) was individually compared to the remaining ones, i.e., perforation with a burr without tapping of the pedicular canal (technique 2), perforation with a Kirschner wire with tapping of the pedicular canal (technique 3), and perforation with a probe without tapping of the pedicular canal (technique 4). Three experimental groups were used according to orifice preparation. Group I was used to compare technique 1 to technique 2, with a study of the effect of tapping on the pedicular canal. Group II was used to compare technique 1 with technique 3, with a study of the effect of mode of orifice preparation using a Kirschner wire. Group III was used to compare technique 1 to technique 4, with a study of the effect of the use of a probe for orifice preparation. Comparison of the techniques of orifice preparation according to the parameters studied (maximum pullout load, stiffness, load in the proportionality limit, maximum dislocation, and dislocation in the proportionality limit) showed no statistically significant difference between the various techniques used for preparation of the orifices of the vertebral pedicle, in terms of their effect on the pullout resistance of the implants.

A marcha humana, ou caminhada, é um padrão cíclico de movimentos corporais que se repetem a cada passo que desloca um indivíduo de um local a outro. Atualmente, avaliações biomecânicas da marcha humana tem sido utilizado no diagnóstico de alterações neuromusculares, músculo-esqueléticas e como forma de avaliação pré e pós-tratamento cirúrgico, medicamentoso e/ou fisioterapêutico. O presente trabalho apresenta o desenvolvimento de uma ferramenta acadêmica de baixo custo para o estudo da marcha humana. Esse sistema consiste no sensoriamento da marcha de um usuário através de sensores inerciais e de um modelo virtual do corpo humano para permitir a visualização do movimento gerado. Dessa maneira o usuário poderá ter suas ações corrigidas por sua percepção visual e também corrigida pelas orientações de um fisiatra ou fisioterapeuta que terá a reprodução do modelo virtual conforme a movimentação detalhada do paciente para análise. O sistema ainda efetuará os registros das variáveis cinemáticas da marcha (tais como aceleração, velocidade angular, angulações dos membros sensoriados) para estudos e acompanhamento mais detalhado da sua recuperação e/ou tratamento. Como resultado, o sistema desenvolvido obteve erros médios de X 0,52º Y 1,20º Z 1,80º e erros em RMS de X 3,01º Y 3,30º Z 5,70º quando comparados com um sistema comercial, sendo esse resultado próximo à literatura e aplicável em exames biomecânicos de marcha. / The human gait is a cyclical pattern of body movements that are repeated every step that moves a subject from one location to another. Currently, biomechanical assessments of human gait has been used for diagnosing neuromuscular disorders, musculoskeletal and as a way of pre and post-surgical treatment, medication and/or physical therapy. This paper presents the development of a low cost academic tool for the study of human gait. This system consists of sensing the motion of a user through inertial sensors and a virtual model of the human body to allow the visualization of the generated movement. In this way, the user can have its actions corrected by his visual perception and also corrected by therapist or physiotherapist who will visualize the virtual model as the detailed movements of patient. The system will also record the kinematic gait variables (as acceleration, angular velocity, angles of the sensed members) for studies and more detailed monitoring of their recovery and/or treatment. As result, the developed system obtained average errors of X 0,52º Y 1,20º Z 1,80º and errors in RMS X 3,01º Y 3,30º Z 5,70º compared to a commercial system, and these results close to the ones seen in literature and applicable in biomechanical tests of gait.

Proximal humerus fractures are the third most common fractures in the over-65 patient population and their stable fixation remains a key challenge in orthopaedic and trauma surgery. While Open Reduction Internal Fixation by plate has become a well-known treatment modality in the last few decades, clinical studies associate high complication rate with its use. The overall aim of this project was to create a computer-aided design framework for proximal humerus plates using a validated subject-specific humerus-plate finite element model. The framework consisted of three stages: (1) reverse engineering of bone and plate geometry, (2) creation and validation of a finite element model simulating the in vitro testing of the bone-implant construct and (3) parametric optimisation study of implant design using this model. In vitro biomechanical tests were conducted to not only compare the mechanical performance of three key commercially available proximal humerus plates (S3-, Fx- and PHILOS plate) but also the effect of different screw zones. Sixty-five humeri specimens with two-part surgical neck fractures were treated and grouped based on their different screw configurations. Extension, flexion, varus and valgus bending were applied in the cantilever fashion in the elastic tests whereas only varus bending was applied in the plastic tests. The load required to apply 5 mm displacement was measured to determine bone-plate construct stiffness. The S3 plate yielded the stiffest constructs and while the removal of the inferomedial support had the most impact on varus bending stiffness, type of medial support was important: inferomedial screws in the Fx plate achieved higher bending stiffness than blade insertion. Stability of constructs treated with the plate was an interplay of factors such as the plate’s and screws' number, orientation and position. Next, a subject-specific finite element model of the humerus-plate construct was successfully developed that simulated the stiffest of the constructs from the in vitro varus bending tests conducted in this project. The model was validated against the in vitro results. The validated model was then used to perform a parametric optimisation study where the combination of design parameters (height and divergence angle of S3 plate’s inferomedial screws) was determined that achieved optimum bone-plate construct stability (minimum fracture gap change). Out of the 538 designs tested, the optimum design (16o divergence angle and 33o height angle) yielded the lowest fracture gap change (0.156 mm) which was 4.686% lower than the standard finite element model while achieving 5.707% higher varus bending load (54.753 N). The validated model was also used to investigate the issue of using smooth pegs and threaded screws. Twenty-six models with different percentages of screw threading were run to compare their bone-plate construct stiffness. While threading the smooth pegs was found to increase the varus bending stiffness by up to 4.546%, it did not affect all screws equally. Finally, the successful completion of the optimisation study of screw orientation and the clinical investigation promises the implementation of the computational framework for a range of future multi-objective optimisation studies of multiple design parameters especially for the design of implants for other parts of the human body and also for investigations into other clinically relevant questions.

A marcha humana, ou caminhada, é um padrão cíclico de movimentos corporais que se repetem a cada passo que desloca um indivíduo de um local a outro. Atualmente, avaliações biomecânicas da marcha humana tem sido utilizado no diagnóstico de alterações neuromusculares, músculo-esqueléticas e como forma de avaliação pré e pós-tratamento cirúrgico, medicamentoso e/ou fisioterapêutico. O presente trabalho apresenta o desenvolvimento de uma ferramenta acadêmica de baixo custo para o estudo da marcha humana. Esse sistema consiste no sensoriamento da marcha de um usuário através de sensores inerciais e de um modelo virtual do corpo humano para permitir a visualização do movimento gerado. Dessa maneira o usuário poderá ter suas ações corrigidas por sua percepção visual e também corrigida pelas orientações de um fisiatra ou fisioterapeuta que terá a reprodução do modelo virtual conforme a movimentação detalhada do paciente para análise. O sistema ainda efetuará os registros das variáveis cinemáticas da marcha (tais como aceleração, velocidade angular, angulações dos membros sensoriados) para estudos e acompanhamento mais detalhado da sua recuperação e/ou tratamento. Como resultado, o sistema desenvolvido obteve erros médios de X 0,52º Y 1,20º Z 1,80º e erros em RMS de X 3,01º Y 3,30º Z 5,70º quando comparados com um sistema comercial, sendo esse resultado próximo à literatura e aplicável em exames biomecânicos de marcha. / The human gait is a cyclical pattern of body movements that are repeated every step that moves a subject from one location to another. Currently, biomechanical assessments of human gait has been used for diagnosing neuromuscular disorders, musculoskeletal and as a way of pre and post-surgical treatment, medication and/or physical therapy. This paper presents the development of a low cost academic tool for the study of human gait. This system consists of sensing the motion of a user through inertial sensors and a virtual model of the human body to allow the visualization of the generated movement. In this way, the user can have its actions corrected by his visual perception and also corrected by therapist or physiotherapist who will visualize the virtual model as the detailed movements of patient. The system will also record the kinematic gait variables (as acceleration, angular velocity, angles of the sensed members) for studies and more detailed monitoring of their recovery and/or treatment. As result, the developed system obtained average errors of X 0,52º Y 1,20º Z 1,80º and errors in RMS X 3,01º Y 3,30º Z 5,70º compared to a commercial system, and these results close to the ones seen in literature and applicable in biomechanical tests of gait.